In the context of, for example, a global satellite cellular communications system, the available channel resources are limited. Such channels must typically carry not only information, such as voice or user data, but also signaling messages to set up and control a user-initiated call, message, or page. In the prior art it is known to assign one of these channels initially to set up a call, which may take up to a minute or longer to accomplish. After this, such channel is used to transmit the user information. This has the disadvantage of tying up a scarce resource during the call setup period. This is inefficient, particularly when it turns out that the call that has been set up cannot even proceed due to blocking at the other end.
Therefore, there is a substantial need for a method and apparatus for transmitting signaling messages over channel resources while minimizing the usage of such channel resources for this purpose.